Solar Cell Receiver Having An Insulated Bypass Diode

ABSTRACT

A solar cell receiver comprising a solar cell having one or more III-V compound semiconductor layers, a diode coupled in parallel with the solar cell and operable to be forward-biased in instances when the solar cell is not generating above a threshold voltage, a coating substantially encapsulating the diode, an undercoating that substantially eliminates any air gap between the anode and cathode of the diode, and a connector adapted to couple to other solar cell receivers.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of this application is related to co-pending U.S.application Ser. No. 11/830,576, filed on Jul. 30, 2007 and U.S.application Ser. No. 11/830,636, filed on Jul. 30, 2007.

TECHNICAL FIELD

This disclosure relates to a solar cell receiver having an insulatedbypass diode.

BACKGROUND

Solar cells are used to convert radiant energy into electricity, and canbe operated at a relatively low cost as the energy generated is receivedfrom the sun.

Typically, a plurality of solar cells are disposed in an array or panel,and a solar energy system typically includes a plurality of such panels.The solar cells in each panel are usually connected in series, and thepanels in a given system are also connected in series, with each panelhaving numerous solar cells. The solar cells in each panel could,alternatively, be arranged in parallel.

Historically, solar power (both in space and terrestrially) has beenpredominantly provided by silicon solar cells. In the past severalyears, however, high-volume manufacturing of high-efficiencymulti-junction solar cells has enabled the use of this alternativetechnology for power generation. Compared to Si, multi-junction cellsare generally more radiation resistant and have greater energyconversion efficiencies, but they are also heavier (higher density andthickness) and tend to cost more. Some current multi-junction cells haveenergy efficiencies that exceed 27%, whereas silicon technologiesgenerally reach only about 17% efficiency. When the need for very highpower or smaller solar arrays are paramount in a spacecraft or othersolar energy system, multi-junction cells are often used instead of, orin hybrid combinations with, Si-based cells to reduce the array size.

Generally speaking, the multi-junction cells are of n-on-p polarity andare composed of InGaP/(In)GaAs III-V compounds. III-V compoundsemiconductor multi-junction solar cell layers can be grown viametal-organic chemical vapor deposition (MOCVD) on Ge substrates. Theuse of the Ge substrate has two advantages over III-V compoundsemiconductor substrates such as GaAs: lower cost and higher structuralbreakage strength. The solar cell structures can be grown on 100-mmdiameter (4 inch) Ge substrates with an average mass density of about 86mg/cm². In some processes, the epitaxial layer uniformity across aplatter that holds 12 or 13 Ge substrates during the MOCVD growthprocess is better than 99.5%. Each wafer typically yields two large-areasolar cells. The cell areas that are processed for production typicallyrange from 26.6 to 32.4 cm². The epi-wafers can be processed intocomplete devices through automated robotic photolithography,metallization, chemical cleaning and etching, antireflection (AR)coating, dicing, and testing processes. The n- & p-contact metallizationis typically comprised of predominately Ag with a thin Au cap layer toprotect the Ag from oxidation. The AR coating is a dual-layerTiO_(x)/Al₂O₃ dielectric stack, whose spectral reflectivitycharacteristics are designed to minimize reflection at thecoverglass-interconnect-cell (CIC) or solar cell assembly (SCA) level,as well as, maximizing the end-of-life (EOL) performance of the cells.

In some multi-junction cells, the middle cell is an InGaAs cell asopposed to a GaAs cell. The indium concentration may be in the range ofabout 1.5% for the InGaAs middle cell. In some implementations, such anarrangement exhibits increased efficiency. The InGaAs layers aresubstantially perfectly lattice-matched to the Ge substrate.

Regardless of the type of cell used, a known problem with solar energysystems is that individual solar cells can become damaged or shadowed byan obstruction. For example, damage can occur as a result of exposure ofa solar cell to harsh environmental conditions. The current-carryingcapacity of a panel having one or more damaged or shadowed solar cellsis reduced, and the output from other panels in series with that panelreverse biases the damaged or shadowed cells. The voltage across thedamaged or shadowed cells thus increases in a reverse polarity until thefull output voltage of all of the panels in the series is applied to thedamaged or shadowed cells in the panel concerned. This causes thedamaged or shadowed cells to breakdown.

As a typical solar cell system has thousands of solar cells, its voltageoutput is normally in the range of hundreds of volts, and its currentoutput is in the range of tens of amperes. At these output power levels,if the solar cell terminals are not protected, uncontrollable electricdischarge in the form of sparks tends to occur, and this can causedamage to the solar cells and to the entire system.

U.S. Pat. No. 6,020,555 describes a solar cell system constituted bypanels, each of which includes multiple solar cells, each solar cellbeing provided with a diode connected between its positive and negativeterminals. The provision of the diodes, typically Schottky bypassdiodes, does go some way to protecting the solar cells against theuncontrollable electric discharges mentioned above. Unfortunately,however, the air gap left between the terminals of each of the diodesdoes not eliminate risks of sparking and shorting, which can still occurif moisture or foreign particles bridge the air gap of such a diode.Thus, although air is a dielectric medium, it has a low dielectricstrength, which means that, when an electric field across an air gapreaches around 3 mv/m, electric current can jump across the air gap anddischarge in the form of sparks. This is referred to as dielectricmedium breakdown.

Another shortcoming of the solar cell system described in U.S. Pat. No.6,020,555 is the inability to manage heat dissipation of the bypassdiodes. At a given moment when a solar cell is being “bypassed,” theassociated diode (assuming a standard system operating at 600-1000 V, 10A) will be conducting 6000-10,000 watts of electrical power, some ofwhich is radiated as thermal energy. Given the small size of thesediodes, their operational life will be substantially shortened if heatis not well managed. Such a shortcoming is even more of a concern whenthe solar cell system is, for example, used in connection with asatellite and is, therefore, not field-reparable. Moreover, passivecooling using heat sinks or the like increases weight and is costly bothin materials and in fabrication/assembly. Active cooling, whileeffective at managing the heat generated by the diodes, is very costlyand heavy, and expends a substantial amount of the energy that the solarcell system generates.

Another disadvantage of known solar cell receivers is that, owing to theneed for such a receiver to generate 10 watts of power at 1000 volts foran extended period of up to, or exceeding, twenty years, there is adanger of sparking at the electrical terminals which connect onereceiver of a solar cell system to adjacent receivers.

SUMMARY

In an aspect of the invention, a solar cell receiver comprises a solarcell having one or more III-V compound semiconductor layers, a diodecoupled in parallel with the solar cell and operable to beforward-biased in instances when the solar cell is not generating abovea threshold voltage, a coating substantially encapsulating the diode, anundercoating that substantially eliminates any air gap between the anodeand cathode of the diode, and a connector adapted to couple to othersolar cell receivers.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective of a solar panel including apparatus forgenerating electricity from solar energy.

FIG. 2 is a perspective view of one solar cell module of the panel ofFIG. 1.

FIG. 3 is a circuit diagram of the solar cell receiver of FIG. 4.

FIG. 4 is a perspective view of a solar cell receiver, which forms partof the solar cell module of FIG. 2.

FIG. 5 is a cross-section taken on line A-A of FIG. 4.

FIG. 6 is a view of the bottom of a solar cell receiver.

FIGS. 7A, 7B and 7C depict an alternate implementation of a solar cell.

DETAILED DESCRIPTION

The following is a description of preferred implementations, as well assome alternative implementations, of a solar cell receiver having aninsulated bypass diode.

Overview

Solar cell receivers convert solar energy into electricity. Toaccomplish this result, solar cell receivers generally comprise one ormore solar cells. A solar cell may be made from, e.g., silicon(including amorphous, nanocrystalline, or protocrystalline), cadmiumtelluride, CIGS (copper indium gallium diselenide), CIS (chalcopyritefilms of copper indium selenide (CuInSe₂)), gallium arsenide (e.g., GaAsmultijunctions), light absorbing dyes (e.g., ruthenium metalorganicdye), or organic semiconductors (e.g., polyphenylene vinylene, copperphthalocyanine or carbon fullerenes). In various implementationsdescribed herein, a triple junction III-V compound semiconductor solarcell is employed, but other types of solar cells could be used dependingupon the application. Solar cell receivers often contain additionalcomponents, e.g., connectors for coupling to an output device or othersolar cell receivers.

For some applications, a solar cell receiver may be implemented as partof a solar cell module. A solar cell module may include a solar cellreceiver and a lens coupled to the solar cell. The lens is used to focusreceived light onto the solar cell. Since a single solar cell module maynot produce sufficient electricity for a given application, two or moresolar cell modules may be grouped together into an array. These arraysare sometimes referred to as “panels” or “solar panels.”

Implementations of a Solar Panel

FIG. 1 depicts an implementation of a solar panel 10, for generatingelectricity from solar energy. The panel 10 includes a plurality ofsolar cell modules 20. In this illustration, twenty-four solar cellmodules 20 are shown. A plurality of similar panels 10 can be combinedto provide a solar energy generating system of greater capacity. Where aplurality of panels 10 are provided, they are normally connected inseries, but other implementations may connect the panels in parallel orseries-parallel.

Implementations of a Solar Cell Module

As shown in FIG. 2, each solar cell module 20 includes a lens 22 (e.g.,a Fresnel lens) and a solar cell receiver 12 positioned at opposite endsof a housing 21. The solar cell receiver includes a solar cell 30. Insome implementations, the housing is in the shape of a trapezoidalsolid, e.g., face 201 is larger than face 202.

In some implementations, the solar cell 30 is a triple-junction III-Vsolar cell, with each of the three sub-cells arranged in series. Inapplications where multiple solar cell modules 20 are employed, thereceivers 12 of the solar cell modules 20 are typically electricallyconnected together in series. However, other applications may utilizeparallel or series-parallel connection.

Implementations of a Solar Cell Receiver

FIG. 3 illustrates the circuit diagram of the receiver 12 of one of thesolar cell modules 20. The receiver 12 includes a triple-junction III-Vcompound semiconductor solar cell 30 which is constituted by a top cell30 a, a middle cell 30 b and a bottom cell 30 c arranged in series.

When implemented in a solar cell module, the solar cell 30 is positionedto receive focused solar energy from the lens 22 (see FIG. 2). In someimplementations, the lens 22 is configured such that sunlight incidentupon the lens is concentrated by a factor of at least 100 onto the solarcell 30. The lens 22 may also comprise a multi-layer anti-reflectivecoating, similar to the one applied to the solar cell 30.

A diode 14 is connected in parallel with the triple-junction solar cell30. In some implementations, the diode 14 is a semiconductor device suchas a Schottky bypass diode or an epitaxially grown p-n junction. Forpurposes of illustration, diode 14 is a Schottky bypass diode. Externalconnection terminals 43 and 44 are provided for connecting the solarcell 30 and diode 14 to other devices, e.g., adjacent receivers 12. Insome implementations, the solar cell 30, the diode 14 and the terminals43 and 44 are mounted on a board or substrate (see, e.g., item 9 of FIG.4) which is made of insulating material.

The functionality of the diode 14 can be appreciated by consideringmultiple solar cell receivers 12 connected in series. Each of the triplejunction solar cells 30 can be envisioned as a battery, with the cathodeof each of the diodes 14 being connected to the positive terminal of theassociated “battery” and the anode of each of the diodes being connectedto the negative terminal of the associated “battery.” When one of theserially-connected solar cells 30 becomes damaged or shadowed, itsvoltage output is reduced or eliminated (e.g., to below a thresholdvoltage associated with the diode 14). Therefore, the associated diode14 becomes forward-biased, and a bypass current flows only through thatdiode 14 (and not the solar cell 30). In this manner, the non-damaged ornon-shadowed solar cells continue to generate electricity from the solarenergy received by those solar cells. If not for the diode 14,substantially all of the electricity produced by the other solar cellreceivers 12 will pass through the shadowed or damaged solar cell 30,destroying it, and creating an open circuit within, e.g., the panel orarray.

FIGS. 4, 5 and 6 illustrate one of the receivers 12. For purposes ofthis implementation, it is assumed that all of the other receivers in agiven panel (e.g., item 10 of FIG. 1) are substantially the same.

FIG. 4 illustrates one solar cell 30 and its associated diode 14. Thesolar cell 30 is electrically connected to the diode 14. The uppersurface of the solar cell 30 comprises a contact area 301 that, in thisimplementation, occupies the perimeter of the solar cell 30. In someimplementations, the contact area 301 is smaller or larger toaccommodate the desired connection type. For example, the contact area301 may touch only one, two or three sides (or portions thereof) of thesolar cell 30. In some implementations, the contact area 301 is made assmall as possible to maximize the area that converts solar energy intoelectricity, while still allowing electrical connection. While theparticular dimensions of the solar cell 30 will vary depending on theapplication, standard dimensions are about 12.58 mm×12.58 mm overall,0.160 mm thick, and a total active area of about 108 mm². For example,in a solar cell 30 that is approximately 12.58 mm×12.58 mm, the contactarea 301 is about 0.98 mm wide. The contact area 301 may be formed of avariety of conductive materials, e.g., copper, silver, and/orgold-coated silver. In this implementation, it is the n-conductivityside of the solar cell 30 that receives light, and accordingly, thecontact area 301 is disposed on the n-conductivity side of the solarcell 30.

An anti-reflective coating 305 may be disposed on the solar cell 30. Theanti-reflective coating 305 may be a multi-layer antireflective coatingproviding low reflectance over a certain wavelength range, e.g., 0.3 to1.8 μm. An example of an anti-reflective coating is a dual-layerTiO_(x)/Al₂O₃ dielectric stack.

The contact 301 is coupled to a conductor trace 302 that is disposed onthe board 9. In this implementation, the contact 301 is coupled to theconductor trace 302 by a plurality (twelve in this example) of wirebonds 304. The number of wire bonds 304 utilized in a particularimplementation can be related, among other things, to the amount ofcurrent generated by the solar cell 30. Generally, the greater thecurrent, the greater number of wire bonds that are used.

The conductor trace 302 (and hence, the solar cell 30) couples toterminal 11 of the diode 14 by way of an electrical connection betweenconductor trace 302 and conductor trace 45.

The other terminal 13 of the diode 14 is coupled to trace 46. Tocomplete the parallel connection between the solar cell 30 and the diode14, terminal 13 is coupled to the underside of the solar cell 30. Thisis discussed in greater detail in connection with FIGS. 5 and 6.

By way of traces 45 and 46, the diode 14 is electrically coupled to theconnector terminals 43 and 44, respectively. The connector terminals 43and 44 are electrically coupled to sockets 343 and 344, respectively,mounted in the apertures 42 and 41 of connector 40. Sockets 343 and 344are shown in dotted lines because they are hidden from view by the bodyof the connector 40. The sockets comprise an electrically conductivematerial (e.g., copper, silver, gold and/or a combination thereof) andprovide for electrical coupling of a device to the circuit. In someimplementations, the sockets correspond to anode and cathode terminals,and are designed to accept receptacle plugs 341 and 342 for connectionto the adjacent receivers 312, e.g., as described above with referenceto FIG. 3. Adjacent receivers 312 may take substantially the same formas receiver 12. The connector 40, is in some implementations, securelyattached to the board 9 and may be constructed out of an insulatingmaterial (e.g., plastic).

The relatively large connector 40, which defines insulated apertures 41and 42, helps prevent a solar cell breakdown as a result of electricdischarges at the terminals leading to adjacent receivers, owing to theinsulated apertures providing an excellent insulation for each of theplug/socket electrical connections housed therein.

As shown in FIG. 5, the diode 14 is mounted above the board 9 on theterminals 11 and 13. Depending on the application, diode 14 may be asurface-mount type.

Terminals 11 and 13 couple to anode and cathode of the diode 14,respectively, and thus may be referred to as the anode terminal orcathode terminal of the diode 14. The portions of the diode 14 asidefrom the terminals 11 and 13 may be referred to as the diode body (i.e.,hatched region 504).

In this implementation, diode terminal 11 is coupled electrically to aconnector 501 that passes through the board 9 to couple the diode to thebottom surface of the solar cell 30. In some implementations, connector501 may take the form of pin that is attached to the diode 14, and ismounted using through-hole technology. The connector 501 may varydepending upon how the solar cell 30 is mounted on the board 9. If, forexample, the board 9 is constructed so that bottom of the solar cell(e.g., the p-conductivity side) is exposed, the connector 501 may passthrough the entire thickness of the board 9. In some implementations,the bottom of solar cell 30 may sit on top of a surface of the board 9.For such implementations, the connector 501 may couple to a layer of theboard 9 (e.g., a layer below the top surface 505 of the board 9).

The gap between bottom portion 503 the diode 14 (e.g., the surface(s)that face the board 9) and the board 9 is occupied by any suitabledielectric underfill material 15, so that there is no air gap betweenthe diode and the board. In some implementations, there is no air gapbetween the contacts 11 and 13 and the underfill 15 occupiessubstantially all of the space between the bottom portion 503 of thediode 14 and the board 9. In that case, the underfill 15 is in contactwith the bottom portion 503 of the diode 14 and the board 9. Theunderfill 15 may also contact other areas of the diode 14. Examples ofsuitable underfill materials include silicone. Similarly, a suitabledielectric globtop (or conformal coating) material 16 is deposited overthe diode 14 so that the diode is encapsulated. The coating 16 isdisposed over the top surface 502 of the diode 14 (e.g., the surface(s)that face away from the board 9) and extends downwardly until it reachesthe board 9. The coating 16 thus encapsulates the diode body 504 as wellas contacts 11 and 13. The coating 16 contacts the top surface 502 ofthe diode 14 as well as contacts 11 and 13. The coating 16 may contactother areas of the diode 14. Suitable globtop or conformal coatingmaterials include those sold under the Loctite® brand by the HenkelCorporation. As the dielectric material 15 and 16 has a much higherdielectric strength than air, the risk of dielectric medium breakdown issubstantially eliminated. The underfill and globtop dielectric materials15 and 16 prevent uncontrolled discharge of electricity, and so protectthe solar cells 30 of the system.

FIG. 6 depicts the bottom side of the receiver 12. The underside 601 ofthe solar cell 30 is a conductive (e.g., metallized) surface. Theunderside 601 may comprise copper, silver, and/or gold coated silver andis coupled to a conductive trace 602. The conductive trace 602 iscoupled to connector 501, which is coupled to terminal 11 of the diode14 (items 11 and 14 are shown in dotted lines because they are hidden inthis view). The conductive trace 602 may be relatively wide to carry thecurrent generated by the solar cell 30. In some embodiments, a jumperwire is used instead of, or in combination with, the conductive trace602.

Depending upon the implementation, the underside 601 of the solar cell30 may rest upon a surface of the board 9 (e.g., a layer above thebottom surface 506). In other implementations, there may be a cutout inthe board 9 that exposes the underside 601 of the solar cell 30. Thelocation of the conductive trace 602 can vary depending on how the solarcell 30 is mounted. For example, if there is a cutout in the board 9,the conductive trace 602 may be on the bottom surface 506 of the board9. If the solar cell 30 rests upon a layer of the board above the bottomsurface 506, the conductive trace 602 may not be on the bottom surfaceof the board (e.g., it may be disposed on a layer between the top 506and bottom 506 surfaces of the board 9). In such implementations, theunderside 601 of the solar cell and conductive trace 602 could be hiddenin this perspective.

Second Implementation of a Solar Cell

FIGS. 7A, 7B and 7C depict a second implementation of a solar cell 730for use, for example, in a solar cell receiver such as item 12 of FIGS.2 and 4. Solar cell 730 is a multi-junction cell having n-on-p polarityand is composed of InGaP/(In)GaAs III-V compounds on a Ge substrate. Thesolar cell 730 also includes an anti-reflective coating comprising adual-layer TiO_(x)/Al₂O₃ dielectric stack, whose spectral reflectivitycharacteristics are designed to minimize reflection at thecoverglass-interconnect-cell (CIC) or solar cell assembly (SCA) level,as well as, maximizing the end-of-life (EOL) performance of the cells.FIGS. 7A and 7B are from the perspective of the n-polarity side.

One difference between this solar cell 730 and the solar cell 30 of FIG.4 is that cell 730 utilizes two terminals 703 and 704 (“bus bars”)rather than the perimeter contact 301 of cell 30. The terminals 703 and704 are surrounded by a passivated frame 705 (visible in FIG. 7B, aclose-up of region 701). The region occupied by the contacts 703 and 704is not part of the active area 702 (e.g., a region capable of convertingsolar energy to electricity). One advantage of this implementation isthat a large percentage of the overall surface area is the active area702 because the contacts 703 and 704 occupy just two sides of the cell730.

The overall dimensions of the cell 730 are about 11.18 mm (dimension710) by 10.075 mm (dimension 714). The cell 730 is about 0.185 mm thick(dimension 718). The active area 702 is about 10 mm (dimension 712) by10.075 mm (dimension 714).

The terminals 703 and 704 are about 9.905 mm wide (dimension 715) by0.505 mm high (dimension 717), and are located about 0.085 mm(dimensions 713 and 719) from the edges of the cell 730. Accordingly,the distance from the outer edge of terminal 703 to the outer edge ofterminal 704 is about 11.01 mm (dimension 711). The passivated frame 705around the terminals 703 and 704 is about 0.01 mm thick (dimension 720).To account for variations in processing (e.g., saw curf), someimplementations employ a thin border (e.g., 0.035 mm, dimension 716)around the entire cell 730 where there are no features.

The bottom of cell 730 (i.e., the p-polarity side) is substantiallysimilar to that of cell 30 illustrated in FIG. 6.

Other Results

In addition to solving the problem of uncontrolled discharge, the use ofthe underfill and/or globtop (e.g., conformal coating) can result inadditional, unexpected, advantages.

Using underfill and/or globtop can substantially improve the ability ofa receiver to manage heat dissipation. The underfill and globtopdielectric materials 15 and 16 have a higher thermal conductivity thanair. Consequently, they improve heat dissipation from the components ofthe system to the surrounding ambient atmosphere by increasing thecross-section of the thermal path. Moreover, because the underfill andglobtop dielectric materials 15 and 16 are, in some implementations, incontact with the board or substrate, they facilitate heat transfer fromthe diode to the board. For example, the underfill 15 and globtop 16substantially improve the heat dissipation of the diode 14. As describedabove, when bypassing the solar cell 30, the diode 14 may be carryingseveral thousand (e.g., 10,000) watts of electrical power. Becausediodes are not perfectly efficient electrical conductors, some of thatpower is dissipated as thermal energy. Excessive thermal energy candestroy the diode, and at a minimum, reduce its service life. As aresult, receivers that employ underfill and/or globtop are likely tohave increased service life, especially as power levels increase.Moreover, the underfill and/or globtop is a much more cost effective,efficient and lighter solution than many other methods (e.g., passivecooling using metal heat sinks or active cooling) for improving heatmanagement. Moreover, those other methods do not solve the problem ofuncontrolled discharge.

The underfill and/or globtop materials can also protect against shortcircuits due to contaminants. In some implementations, the conductortraces (e.g., items 45 and 46) are separated by no more thanapproximately 1 mm (0.394 inches). When traces are about this close toeach other, many contaminants, such as a droplet of water, aresufficiently large to contact two adjacent conductor traces. Moreover,as the diode 14 is itself relatively small, and it is possible for oneor more water droplets to bridge terminals 11 and 13. Since solarreceivers 12 often are used outdoors, they are exposed to moisture, forexample, from condensation and/or rain. The use of the underfill and/orglobtop prevents moisture from condensing on the terminals of the diode14 or on the conductor traces 45 and 46, thereby reducing theprobability of short circuits.

The underfill and/or dielectric globtop (or conformal coating) materials15 and 16 also prevent foreign materials falling onto the terminals ofthe diodes 14, onto the conductor traces 45 and 46 and onto anyelectrical traces on the board 9, thereby further reducing theprobability of short circuits during operation.

Another unexpected advantage is that the underfill and/or globtopdielectric materials 15 and 16 add mechanical integrity to theinterfaces between the diodes 14 and the boards 9 to which they areattached. As a result, during transport, installation and handling, thelikelihood of the diode 14 becoming detached (or otherwise electricallyde-coupled) is reduced.

Typical Performance Data

Testing implementations of solar cell receivers (e.g., item 12) atdifferent solar concentrations resulted in the following data:

1 Sun 470 Suns 1150 Suns Efficiency 31.23% 36.23% 33.07% V_(oc) (opencircuit 2.583 V 3.051 V 3.078 V voltage) J_(sc) (short circuit 13.9mA/cm² 6.49 A/cm² 15.92 A/cm² current) V_(mp) (voltage at 2.32 V 2.704 V2.523 V maximum power point) J_(mp) (current at 13.46 mA/cm² 6.27 A/cm²15.04 A/cm² maximum power point) P_(mp) (maximum 31.23 mW/cm² 17.03W/cm² 38.03 W/cm² power point)

Principles of the present invention can be applied to terminals, leads,traces and conductors of semiconductor components on substrates,carriers, packages, daughter boards, mother boards, and panels used insolar power systems. The present invention can be applied to all typesof semi-conductors including, but not limited to, bare dye, throughhole, BGA, PGA, LGA and flip chip devices.

It will be apparent that modifications could be made to the apparatusdescribed above. In particular, the dielectric material could be appliednot only to the diodes, but also to all terminals, leads, and conductortraces on the panel. Moreover, the present invention can be used toapply a dielectric coating to any form of conductors and substrates usedin solar power systems.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the invention. Accordingly, otherimplementations are within the scope of the claims.

1. An apparatus for converting solar energy to electricity comprising: asubstrate; a solar cell, on the substrate, comprising one or more III-Vcompound semiconductor layers, a first contact coupled to a p-polarityside of the cell and a second contact coupled to an n-polarity side ofthe cell; a diode, on the substrate, comprising a body, an anode contactand a cathode contact, the diode coupled in parallel with the first andsecond contacts of the solar cell such that the anode contact of thediode is coupled to the first contact and the cathode contact of thediode is coupled to the second contact, wherein the diode body comprisesa top portion and a bottom portion, the bottom portion being disposedcloser to the substrate than the top portion; a coating disposed overthe top portion of the diode body and extending to the substrate, thecoating substantially encapsulating the diode body, anode contact andcathode contact; an undercoating occupying substantially all of thespace between the bottom portion of the diode body and the substrate;and output terminals coupled to the solar cell and the diode.
 2. Theapparatus of claim 1 wherein the undercoating is disposed such thatthere is no air gap between the diode and the substrate.
 3. Theapparatus of claim 1 wherein the undercoating comprises silicone.
 4. Theapparatus of claim 1 wherein the undercoating and coating have a higherdielectric strength than air.
 5. The apparatus of claim 1 wherein theundercoating and coating have a higher thermal conductivity than air. 6.The apparatus of claim 1 comprising a connector coupled to the outputterminals, the connector being operable to provide electrical connectionto one or more solar cell receivers, the connector comprising: twoapertures electrically insulated from each other, one aperturecomprising a first electrical socket and one aperture comprising asecond electrical socket, the anode contact of the diode and the firstcontact are electrically coupled to the first electrical socket and thecathode contact of the diode and the second contact are electricallycoupled to the second electrical socket.
 7. A solar cell receivercomprising: a board; a solar cell mounted on the board, the solar cellcomprising one or more III-V compound semiconductor layers, a firstcontact coupled to a p-polarity side of the cell and a second contactcoupled to an n-polarity side of the cell; a diode mounted on the board,the diode comprising a body, an anode contact and a cathode contact,wherein the diode body comprises a top portion and a bottom portion, thebottom portion being disposed closer to the board than the top portion;a coating disposed over the top portion of the diode body and extendingto the board, the coating substantially encapsulating the diode body,anode contact and cathode contact; an undercoating occupyingsubstantially all of the space between the bottom portion of the diodebody and the board; a first conductive trace coupling the anode contactof the diode to the first contact; a second conductive trace couplingthe cathode contact of the diode the second contact; a connector,mounted to the board, comprising first and second sockets electricallyinsulated from one another; a third conductive trace coupling the anodecontact to the first socket; and a fourth conductive trace coupling thecathode contact to the second socket.
 8. The solar cell receiver ofclaim 7 wherein the diode comprises a Schottky bypass diode.
 9. Thesolar cell receiver of claim 7 wherein the second contact compriseselectrically conductive material disposed on the perimeter of then-polarity side of the solar cell.
 10. The solar cell receiver of claim7 wherein the second contact comprises electrically conductive materialdisposed adjacent to two edges of the n-polarity side of the solar cell.11. The solar cell receiver of claim 7 comprising one or more wire bondsthat couple the second contact to the second conductive trace.
 12. Thesolar cell receiver of claim 7 wherein the first contact comprises ametal layer disposed on substantially the entire p-polarity side of thesolar cell.
 13. The solar cell receiver of claim 7 wherein the secondconductive trace is disposed on a second surface of the board and thefirst conductive trace is disposed on a first surface of the board. 14.The solar cell receiver of claim 7 wherein the connector is adapted toprovide electrical connection to one or more solar cell receivers. 15.The solar cell receiver of claim 7 wherein the connector comprisesplastic.
 16. The solar cell receiver of claim 7 wherein the diode isoperable to prevent current flow through the solar cell in instanceswhen the solar cell is not generating above a threshold voltage.
 17. Areceiver for converting solar energy to electricity comprising: a solarcell comprising one or more III-V compound semiconductor layers; a diodehaving an anode terminal and cathode terminal, the diode coupled inparallel with the solar cell and operable to be reverse-biased ininstances when the solar cell is generating above a threshold voltageand forward-biased in instances when the solar cell is not generatingabove a threshold voltage; a coating encapsulating the diode; anundercoating disposed below the diode and between the anode terminal andcathode terminal; and a connector connected in parallel with the solarcell and the diode.
 18. The receiver of claim 17 wherein the solar cellis a multi-junction cell comprising at least one layer comprising InGaP,InGaAs or GaAs.
 19. The receiver of claim 17 wherein the connector isoperable to provide electrical connection to one or more solar cellreceivers.
 20. The receiver of claim 17 wherein the undercoating isdisposed such that there is no air gap between the anode terminal andthe cathode terminal.
 21. An apparatus comprising: first means forconverting solar energy into electricity; second means for substantiallypreventing current flow through the first means in instances when thefirst means is not generating above a threshold voltage; third means forencapsulating the second means; fourth means for preventing shorting ofthe second means; and output means coupled to the first means and thesecond means.
 22. A solar cell receiver comprising: a substrate forsupporting components; a solar cell, mounted on the substrate, forconverting solar energy into electricity; a diode, mounted on thesubstrate, having terminals and coupled in parallel with the solar cell,the diode operable to substantially prevent current flow through thesolar cell in instances when the solar cell is not generating above athreshold voltage, the diode having a first area facing the substrateand a second area facing away from the substrate; a coating thatencapsulates the diode, the coating in contact with the second area ofthe diode and the substrate; an undercoating to prevents shorting of thediode terminals, the undercoating disposed between the diode terminalsand in contact with the first area of the diode and the substrate; andan output structure, coupled to the diode and the solar cell, adapted tocouple to at least one other solar cell receiver.
 23. The solar cellreceiver of claim 22 wherein the solar cell is a multi-junction cellcomprising at least one layer comprising InGaP, InGaAs or GaAs.
 24. Thesolar cell receiver of claim 22 comprising a lens to focus a source ofsolar energy onto the solar cell.
 25. The solar cell receiver of claim22 wherein the solar cell comprises an anti-reflective coating.